In a robotic system, a plurality of instruments may be telerobotically controlled by an operator to perform a procedure on an object at a work site. A camera is provided at the work site to capture images of end effectors of the instruments as they interact with the object to perform the procedure, so that the operator may view their movements on a display screen while controlling them through associated input devices.
While performing the procedure, it may be necessary to introduce a new instrument to the work site to perform a needed function; replace an instrument already there with a new instrument; replace an end effector on an instrument already there with a new end effector; introduce some accessory item to the work site for performing the procedure by attaching it to an instrument and inserting the instrument to the work site; or remove an item from the work site by attaching it to an instrument, retracting the instrument and removing the item from the instrument, and reinserting the instrument back to the work site so that it may once again be available for use there.
In each of these applications, it may be advantageous to have an assistant control all or a part of these actions while the primary operator continues to perform the procedure using the remaining instruments. Once the new or the retracted and reinserted instrument becomes available at the work site, its control may be transferred to the primary operator so that the instrument is available for use by the primary operator at the work site.
To insert the new or the retracted and reinserted instrument to the work site, however, may be a time consuming and difficult task for the assistant. Also, it may be difficult for the assistant to bring the new or reinserted instrument into the field of view of the on-site camera so that it may be viewed by the primary operator on the display screen before switching control of the instrument to the primary operator. It is also possible for the assistant to misjudge the depth of insertion of the new or reinserted instrument and place its distal end too deep into the work site, which may cause unintended contact between the instrument and objects at the work site. To avoid such unintended and possibly harmful contact, the assistant is likely to move the new or reinserted instrument very slowly into the work site.
U.S. Pat. No. 6,645,196, which is incorporated herein by reference, describes a guided tool exchange procedure employable in a medical robotic system to guide a new tool quickly and precisely, after a tool exchange operation, into close proximity to the operating position of the original tool prior to its removal from a work site.
During the performance of a procedure, however, the camera pose may change so that the camera may get a better view of the working ends of instruments as the instruments move while performing a procedure on an object at the work site. In such a situation, inserting a replacement or reinserting the old instrument to its former position may be undesirable since it may not be a good location for the new instrument and further because it may be outside the current field of view of the camera. In addition, it may be desirable to allow the primary operator to assume control of the new instrument as soon as practical so as not to unduly delay the continued performance of the procedure using the new instrument.